1. Field of the Invention
This invention relates generally to an apparatus and process for ultrasonically identifying and coating articles having differing dimensional characteristics. More specifically, the invention relates to such a process and apparatus wherein articles carried on a conveyor are ultrasonically identified by their dimensions and the resulting information is used to electronically select and initiate an appropriate coating operation by a pre-programmed coating apparatus.
2. Description of the Prior Art
In the past, two methods have been used to select coating programs for robots: manual entry and multiple photocells connected to a programmable controller.
The manual entry task is assigned to an operator at some point preceding the automatic operation. Process codes for all items between this point and the robot must be held in a queue. Errors such as entry of incorrect codes, or mistakes in sequence, both, could result in damage to the equipment or goods. Sequence errors could require considerable down time for re-entry of the queued data.
Systems using photocells and programmable controllers require a unique combination of bright and dark cells for each item. The hardware costs and installation time for these systems can exceed those of the coating system. Adding a single item could require additional photocells and complete retesting of the operation. For example, when articles of furniture are to be coated, the furniture dimensions may vary in a matter of inches or fractions thereof. Using the photocell system would require a prohibitive number of photocells and a rearrangement thereof whenever different articles were to be coated. Thus, the use of photocells would not provide a satisfactorily usable substitute for the apparatus and process of this invention. The diversity of furniture sizes requires a continuous measurement of dimensions, not the greater or smaller indication of a photocell arrangement. Safety features, such as detecting unknown items, add to the hardware costs and depend on the designer's ability to anticipate the characteristics of these items.
Ultrasonic range finding systems are known. Such systems are utilized in connection with the focusing apparatus of cameras and the like, as exemplified by U.S. Pat. Nos. 3,522,764 and 4,199,246. It is further known, as shown by U.S. Pat. No. 4,223,790 to convey articles to a location where their presence is sensed by a photocell arrangement and an electrical signal is generated which, in turn, actuates an ultrasonic wave generator. The ultrasonic waves impinged on an object of the conveyor are reflected, and the waves, which have been modulated by the object at its inherent vibration are received and converted into an electrical signal. The signal is then compared with a stored reference signal to discriminate whether the object is good or bad. An electrical signal is then fed through a drive circuit to a rotary solenoid which appropriately rotates an arm which, either removes the object from the conveyor, or leaves it thereon.
U.S. Pat. No. 3,149,561 relates to a supersonic article locating device that simultaneously checks the indirect dual supersonic reflections of the object together with the change of the reflected signal strength due to a change in its topography. These signals then initiate an operational control of a device which is moved to perform some work on the articles when they are in the proper location.
The known prior art does not teach any apparatus and process capable of applying a customized coating to each of a random series of articles of differing dimensional characteristics by utilizing ultrasonic identifying and control means for the coating means.